There has been relatively little research into the synthesis of group IV nanocrystals (e.g., silicon nanocrystals, germanium nanocrystals) via solution methods despite the interesting optical and electronic properties that make them important for future technological applications. Silicon nanocrystals exhibit visible luminescence. The wavelength of the luminescence is proportional to the size of the nanocrystal. Since silicon is an important electronic material with applications ranging from computer chips to photovoltaics, nanoelectronics based on silicon has tremendous potential. In addition, since silicon is a biocompatible element, there are many possible applications in the field of biology and medicine as an inorganic fluorescent probe, a biosensor, or a drug delivery agent. The largest barrier to the utilization of nanocrystalline silicon is the lack of a high yield synthetic method that gives rise to good quality silicon nanocrystals.
Several possible methods for producing silicon nanoparticles have been attempted. These methods include the gas phase and solution decompostion of silanes, the reactions of silicon Zintl salts with silicon halides as well as the solution reduction of silicon halides by sodium, lithium naphthalenide or hydride reagents or reduction of Si(OEt)4 with sodium. While some of these methods are solution reduction methods, it has been suggested that both high temperatures and pressures achieved by bomb reactions, ultrasonication, or annealing after synthesis are required to generate crystalline silicon. In addition, these techniques often give rise to surface oxide contamination.